Can you remember which issue?
I have it scanned on my computer but can't recall which issue - it's the 2 part Bower article from '96 discussing Space:1999 models in general.
About Alpha it reads:
When they [Eagles] arrived at the studios they ,were
not "dirtied down" but were finished in
matt white primer. Cyril Forster, Ron
Burton and Terry Reed were the three
technicians working mostly with the models
at the studios. They did the dirtying down
processes, added the panel lines and also
built Alpha Moonbase. This was constructed
in perspex and wood and covered with
plasticard and literally thousands of
"Butterfly Brand" paper sticky labels to
represent the slab construction of the base.
They also built many large sections of
Alpha in approximately 1/24th scale, loads
of support gantries for the Eagle hangars,
the various scales of Eagle launch pads and
of course all the landscapes for the Moon
and the various planets visited by the
The Moonscapes around Alpha were
created in Plaster of Paris. This was poured
around the completed model after all the
buildings had been stuck in position, with
the craters being made by flicking water into
the plaster as it dried. (I show this technique
in my Modelling Techniques video Vol 2
quite extensively). The baseboard for Alpha
was some 24 feet square and weighed a ton!
When it was not in use it was hauled on chains
up into the studio roof out of the way!